Few bands are likely to tote a full mariachi band around with them on tour. Yet few bands are so closely associated with a geographical area more than Arizona's Calexico. Named after a town on the California-Mexico border, they're indelibly steeped in the musical tapestry of the south-western US and Latin America, core duo of singer/guitarist Joey Burns and drummer John Convertino combining the fried, widescreen feel of the region's musical heritage with more overt Americana, all soaring pedal steel and rolling drums.

That makes the sight of new LP being titled Algiers something of a jarring one. Fortunately for diehard fans, it's not a reference to the capital of Algeria - there's no experimental flirtation with north African polyrhythms - but to the area of New Orleans where recording took place. It is, however, an attempt to uproot and move away from the signature dusty sound inspired by geography - Burns talked of wanting to record in Europe, "but we never get our stuff together in time to make plans that far in advance. So where do you go that is nearby and has a European feel? New Orleans."

If New Orleans was a half-measure, a compromise instead of Europe, it shows. Not committing to relocation undermines much of the material, not to mention Burns and Convertino's dynamic, interdependent musicianship that's the band's cornerstone. The vintage Calexico sound in the opening salvo of 'Epic' and 'Splitter' is strangely neutered, robbed of its usual swagger, and 'Para' feels like a pale rewrite of 'Black Heart' from 2003's career high Feast of Wire, aiming for a menacing mood which never catches. The band have left the dusty vistas behind before over their 15 year career, most notably on 2006's excellent Garden Ruin which featured the swarming 'All Systems Red', a six minute panicky crescendo of electric guitars, unlike anything they'd tackled previously. If that was the sound of a band pushing limits and working through the gears, Algiers is, unfortunately, often the sound of coasting, of wheels spinning.

It could be that habits formed during recent soundtrack work - notably for Irish black comedy The Guard - have wormed inside Burns and Convertino's heads so they're used to now settling unobtrusively into the background. 'Better and Better' is pure soundtrack fare, not saved by some adept guitar playing, and the Spanish language 'No Te Vayas' just drifts by. The brass flecked title track is lively enough with its woodblock and accordion, but feels like it's just playing to type. Songs in general often feel like extended, languorous mood pieces - hooks lacking barbs and lyrics without an edge, suggesting that most material is either over or underwritten, the band unsure of just where they are or - crucially - are meant to be.

That said, Burns and Convertino are nothing if seasoned pros, and they still deliver some of the goods. The jazzy, peacock strut of 'Sinner on the Sea' is rare evidence of sought-after new influences coming to the fore with its stabs of 60s organ and a rawer, looser vocal. 'Hush' especially is a winner, and is an example of quiet understatement actually paying off in a gorgeous, rising melody underpinned by strings, but comes too little too late buried at the end of the album. Still, there are precious few songs that will trouble setlists in the long term; no equal to 'Two Silver Trees', 'Quattro (World Drifts In)', 'Yours and Mine' or 'Ballad of Cable Hogue'. Sometimes it's best to stick to what you know, not to mention where you're comfortable. Algiers too often lacks the focus and zip of Calexico's early work and is uncharacteristically muted, self-conscious and uncertain. A return to the dustbowl beckons.